A metal complex that exhibits light emission from a triplet excited state can be expected as a light-emitting material used in a light-emitting layer in electroluminescent devices to have higher luminous efficiency than that of a fluorescent material which exhibits light emission from a singlet excited state. For example, an ortho-metalated complex having iridium as a central metal (Ir(ppy)3: Tris-Ortho-Metalated Complex of Iridium(III) with 2-Phenylpyridine), which exhibits green light emission, has been proposed (NON-PATENT DOCUMENT 1) as the metal complex which exhibits light emission from a triplet excited state.    NON-PATENT DOCUMENT 1: APPLIED PHYSICS LETTERS, Vol. 75, p. 4 (1999)